recovery_ui: Tell the user they're actually formatting

* TWRP has given user the sentiment that "Wiping data",
  and "Factory Reset" both imply the exclusion of
  files in `/data/media/0` (/sdcard), whereas both AOSP
  (and Lineage Recovery by proxy) format the partitions.

Change-Id: I36c5a59552d7d538a05762ca262e42dc78a1deac